Question: $ { {2} \times \left[\begin{array}{r}{1} \\ {2} \\ {2}\end{array}\right] = {?} } $
Solution: To multiply a matrix by a number, multiply each item of the matrix by the number. ${\left[\begin{array}{r}{2}\times{1} \\ {2}\times{2} \\ {2}\times{2}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{r}{2} \\ {4} \\ {4}\end{array}\right]}$